Successive in vivo embryo production in Santa Inês sheep

Abstract

Context In vivo embryo production, also called multiple ovulation and embryo transfer, can accelerate genetic gain, and thus improve animal production. However, there are issues limiting a wider use of this biotechnology in sheep livestock. Aims This study aimed to determine (1) whether a previous response to superovulation (SOV) can be used as a criterion to select ewes for in vivo embryo production, (2) whether the intensity of the SOV response (number of corpora lutea, CL) can affect the embryo recovery rate, and (3) whether the number of CL quantified by colour Doppler ultrasonography can be used to calculate the recovery rate. Methods Twenty-five Santa Inês ewes underwent SOV three times (SOV1, SOV2 and SOV3), with 200 mg FSH and natural mating. The number of CL after each SOV was determined by laparoscopy and by colour Doppler ultrasonography. Key results The number of CL significantly decreased (P < 0.05) after SOV1 (7.5 ± 4.8) to 3.0 ± 5.0 at SOV 2 and 2.2 ± 3.5 at SOV3. Strong correlations were observed between SOV2 and SOV3 in terms of numbers of CL (r = 0.86, r2 = 0.74; P < 0.0001) and viable embryos (r = 0.79, r2 = 0.63; P < 00001). However, no correlations were observed between SOV1 and SOV2 or between SOV1 and SOV3. Recovery rate did not differ with the intensity of the SOV response (≤6, 7–10, >10 CL) or between the methods used to quantify CL. Conclusions Ewes did not show the same pattern of response when submitted to successive FSH-based SOV. The intensity of the SOV response did not affect the recovery rate, and the number of CL estimated by colour Doppler ultrasonography can be used to calculate the recovery rate. Implications Selecting sheep embryo donors by a previous SOV response is not always feasible. The recovery rate is homogeneous and it is not affected by the intensity of the SOV response. A nonsurgical technique can be used to assess the recovery rate, improving animal welfare in MOET programs.

Technologies Used in Production Systems for Santa Inês Sheep: A Systematic Review

“…As well as progesterone, other ovulation inducers have been used in protocols, such as human chorionic gonadotropin (eCG) ( 47 ), gonadotropin-releasing hormone (GnRH) ( 48 ), and pFSH in combination with eCG ( 49 ) or successive administration ( 50 ).…”

Hormonal protocol used for cervical dilation in ewes does not affect morphological embryo quality but reduces recovery rate and temporarily alters gene expression

“…Then, the uterus was exposed and the embryo collection by laparotomy was performed in all the animals by the same technician according to Pinto and others. 2 The animals received an anti-inflammatory (0.5 mg/kg intramuscular; Maxican; Ourofino, São Paulo, Brazil) for three following days, and three applications of antibiotic (20 mg/kg intramuscular; Terramicina/LA; Zoetis, São Paulo, Brazil) every 48 h.…”

“…In sheep, the morphological characteristics of the cervix (misaligned cervical rings, a long and/or tortuous cervix) determine that embryos should be col-lected surgically, limiting the practical application of embryo biotechnologies. 1,2 Recently, the non-surgical embryo recovery (NSER) transcervical technique has become an alternative to overcome this problem, [3][4][5] with fewer negative effects on animal welfare. 6 However, this method is not applicable in every condition, as it requires technician's training and experience, and the results vary widely according to the breed, parity, and the use of cervical dilation protocols.…”

Use of meloxicam with or without dipyrone in non‐surgical embryo recovery in hair sheep: Effects on animal welfare

“…Embryo collection and transfer are key steps for the success of these programmes and can be performed by surgical or transcervical techniques. Despite the good outcomes and still being the most commercially used method for sheep, surgical procedures for embryo collection involve several animal welfare issues due to the anaesthetic and surgical risks and a limit of successive donor uses as a consequence of post‐surgical sequelae in reproductive organs (Fonseca et al, 2016; Gomes et al, 2014; Pinto et al, 2020). However, although there are initial studies on pharmacological protocols for cervical dilation (Dias et al, 2023, 2020; Fonseca, Zambrini, et al, 2019; Leite et al, 2018; Prellwitz et al, 2019), the complex sheep's cervical morphology makes transcervical uterine access difficult (Fonseca et al, 2019a; Kershaw et al, 2005).…”